The present invention relates to a method of and an apparatus for measuring the shape of a wavefront of light.
It is known to determine the surface configration of an object by measuring the shape of the wavefront of light that has been reflected by the surface of the object. It is also known to determine the optical performance of a lens by measuring the shape of the wavefront of light that has passed through the lens.
Interference of light waves has been utilized to measure the shape of wavefronts. Known measuring systems employing optical interference include the Twyman-Green interferometer and the shearing interferometer.
These systems for measuring the shape of wavefronts generally include a computation process. The computation process is however subject to errors since parameters contained in the process and dependent on the system arrangement are apt to vary due to temperature changes and vibration.